Genomes of 201 microbes sequenced

Washington: Scientists have successfully sequenced the genomes of 201 microbes to find out more about the role these tiny, single-celled organisms play in our environment.

The genetic secrets of some of the most abundant and diverse forms of life on Earth were uncovered by an international collaboration led by the US Department of Energy Joint Genome Institute (DOE JGI).

From these samples, the team laser-sorted 9,000 cells, from which they were able to reassemble and identify 201 distinct genomes, which then could be aligned to 28 major previously uncharted branches of the tree of life.

"Microbes are the most abundant and diverse forms of life on Earth," said Tanja Woyke, DOE JGI Microbial Program Head and senior author of the study.

"Genome sequencing of the rest of the genomes of most of these lineages is however proceeding much more slowly. Microbial genome representation in the databases is quite skewed," said Chris Rinke, DOE JGI postdoctoral fellow and first author of the study.

The second contribution arising from the work was the correct reassignment, or binning, of data of some 340 million DNA fragments from other habitats to the proper lineage.

This course correction provides insights into how organisms function in the context of a particular ecosystem as well as a much improved and more accurate understanding of the associations of newly discovered genes with resident life forms, researchers said.

The third finding was the resolution of relationships within and between microbial phyla - the taxonomic ranking between domain and class - which led the team to propose two new superphyla.

The 201 genomes provided solid reference points, anchors for phylogeny?the lineage history of organisms as they change over time.

"Our single-cell genomes gave us a glimpse into the evolutionary relationships between uncultivated organisms - insights that extend beyond the single locus resolution of the 16S rRNA tree and are essential for studying bacterial and archaeal diversity and evolution," Woyke said.